1. Field of the Invention
The present invention relates to a rotary heat exchanger and more specifically to a rotary heat exchanger which exhibits good heat exchange characteristics and has an improved seal and bearing structure.
2. Description of the Prior Art
Japanese Published Unexamined Patent Application Nos. -59-41111 and -60-23277 disclose rotary heat exchangers like the one shown in FIGS. 1 and 2. This type of device includes an inlet port 1 through which fluid F is supplied to a supply chamber 2. A seal arrangement 3 supports a supply conduit 4 in a manner wherein the upstream end of the conduit 4 is placed in fluid communication with the supply chamber 2. The downstream end of the supply conduit 4 communicates with an essentially annular rotatable supply header 5. A plurality of hollow blower blades are arranged to establish fluid communication between the outer peripheral portion of the supply header 5 and the corresponding portion of a rotatable exhaust header 7. An exhaust conduit 8 is arranged to communicate at its upstream end with the exhaust header 7 and to be rotatably supported by seal arrangements 9 and 10 in an exhaust chamber 11. The portion of the exhaust conduit 8 defined between the two seal arangements 9 and 10 is apertured so that the fluid which is supplied into the exhaust header 7 can be discharged into the exhaust chamber 11 and subsequently drained therefrom via an outlet conduit 12.
The hollow blower blades 6 are provided with a plurality fins 13 which improve the heat exhange efficiency of the arrangement. A motor 14 is operatively connected to an end portion of the exhaust conduit 8. When this motor 14 is energized the rotary headers 5 and 7 and interconnecting hollow blower blades 6 are induced to rotate and define a rotary blower arrangement.
However, this arrangement has the drawbacks that both the fins 13 which are either in the form of circular or annular plates and the hollow blower blades 6 must be precisely formed and assembled in order to achieve a good fit and balance of the rotating parts. This of course makes their production and assembly time-consuming, which, in combination with the high precision requirements, increases the cost of the device undesirably.
In addition, as air has a finite viscosity, a boundary layer tends to be formed over the surface of the fins 13 and reduces the amount of heat exchange with the air passing through the device. However, if the number of fins 13 are increased to improve this situation, the surface area of the blower blades 6 actually available for inducing the necessary flow of air through the device tends to be reduced and therefore reduces the amount of air which is blown through. This therefore limits the number of additional fins which can be added and therefore causes a number of design limitations.
Further, the seal arrangements 3, 9 and 10 which are provided in order to prevent leakage of the fluid being cooled, are subject to vibration and radially acting forces due to the inevitable slight imbalance in the rotating parts of the device, and tend to readily deteriorate to the point of permitting leakage to occur.